When you use online TurboTax you only get one return per fee. If you need to prepare another return for another family member, etc,. then you need a second account and user ID for that return. If you use the same account and user ID for more than one return you overwrite the first one and lose it forever.
Online is only good for 1 return per account. But you can use the same email address for 5 accounts. How to start another return in the Online version
Unless they all qualify to use the Free Edition or Free File website.
In the regular Turbo Tax Free Edition, information that you can enter is limited.
There is also The Turbo Tax Free File program which is free for federal and state. And has more forms than the Federal Free Edition, like Schedules A, B, C , D, E, F, EIC, H, K-1, SE, etc.
NOTE: You will have to setup a new account with a new username and new password or it will take you back to regular Turbo Tax.
To qualify for the Free File website you just need to meet one of these 3 things.
AGI $36,000 or less.
Active duty military with AGI of $69,000 or less
OR qualify for EIC (earned income credit.)
In order to use the Free File program, you have to start it at a special website. Click on the Orange button I Qualify, Let's get Started and set up a NEW account